WO 2013/090277 A1 discloses a driver comprising an AC-DC-converter coupled to a mains supply, an emergency lighting module coupled to a battery (a re-chargeable source) and a LED control for driving a LED board (a load). The LED board is be powered via the AC-DC-converter in a normal situation and is powered via the emergency lighting module in an emergency situation. The emergency lighting module can in the normal situation be charged via the AC-DC-converter.